linux-kernel - Re: [PATCH 1/3] soc_camera: Add the ability to bind regulators to soc

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Message-ID: <20101130110516.GB7403@rakim.wolfsonmicro.main>
Date:	Tue, 30 Nov 2010 11:05:17 +0000
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Alberto Panizzo <maramaopercheseimorto@...il.com>
Cc:	Guennadi Liakhovetski <g.liakhovetski@....de>,
	Mauro Carvalho Chehab <mchehab@...radead.org>,
	Hans Verkuil <hverkuil@...all.nl>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Magnus Damm <damm@...nsource.se>,
	M?rton N?meth <nm127@...email.hu>, linux-media@...r.kernel.org,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] soc_camera: Add the ability to bind regulators to
 soc_camedra devices

On Tue, Nov 30, 2010 at 11:45:23AM +0100, Alberto Panizzo wrote:
> On lun, 2010-11-29 at 15:51 +0000, Mark Brown wrote:

> > Unless you're actively varying the voltages at runtime (as Guennadi
> > mentioned) I'd really expect the voltages to be handled by the regulator
> > constraints.

> This is sane thinking at a static board configuration. What if a single 
> board have different deploying schemas where two different cameras can 
> be placed on the same connector and these cameras have different voltage
> levels for core supply? This scenario will require two different 
> constraints chosen at compile time -> two different kernel binaries.
> Otherwise constraints will always pick the minimum level and maybe this 
> will not be enough.

The way I'd expect to see that handled is that the constraints would be
chosen when the module is detected, possibly by having a platform device
representing the assembly as a whole.  There was someone working with
plugin modules doing something along those lines.  I certainly wouldn't
expect the device itself to worry about this unless it was actively
doing something to manage the voltage.
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